Hyperelastic Bone Produced by 3D Printing Could be Effective for Fixing Skull Defects

Defects of the facial bones and skull are found to be the major challenges for plastic and reconstructive surgeons.

A study reported in the May issue of Plastic and Reconstructive Surgery, the official medical journal of the American Society of Plastic Surgeons (ASPS), described that hyperelastic bone, which is a synthetic material that can be readily synthesized by 3D printing, could provide an effective new tool for fixing the skull defects.

In the study by Ramille N. Shah, PhD, and collaborators from Northwestern University and the University of Illinois Health, Chicago, the primary results showed that the experimental material could speed up bone regeneration across skull defects in rats. The scientists explained, “Hyperelastic bone has significant potential to be translated to craniofacial reconstructive surgery, where the need for cost-effective bone replacement grafts is enormous.”

Promising New 3D-Printed Bone Replacement for Skull Reconstruction

The scientists reported their primary experiments with hyperelastic bone in rats with surgically developed defects on the top of the skull. The surgically formed defects were of a “critical size” not possible to heal on their own—just as those seen in patients who have been subjected to surgery for brain tumors.

Hyperelastic bone is a “3D-printed synthetic scaffold,” comprising chiefly of bone mineral (hydroxyapatite) and an extensively used, biocompatible material (polyglycolic acid). Hyperelastic bone comprises of an intricate latticework, developed to facilitate the growth and regeneration of new bone. It can be produced at high speed and low cost using existing 3D-printing hardware platforms and can be easily pressed to fit or cut into shape without breaking during surgery.

In the experiments, few skull defects were restored using hyperelastic bone, whereas others were fixed using the animal’s own (autologous) bone. Autologous bone is the ideal material for bone defect reconstruction but it is difficult to obtain—which needs bone to be taken from a “donor site” somewhere else in the body—and sometimes is hardly available. In other animals, reconstruction was carried out using a scaffold made of polyglycolic acid only, without bone mineral.

The 3D-printed hyperelastic bone offered excellent bone regeneration. On follow-up CT scans, the hyperelastic bone was approximately 74% effective after 8 weeks and 65% at 12 weeks, in comparison with the autologous bone. Conversely, defects treated using the polyglycolic acid scaffold exhibited very less formation of new bone.

Microscopic examination revealed that the hyperelastic bone scaffold was slowly surrounded first by fibrous tissue and later by new bone cells. As time passed, there was a complete scaffold replacement by new bone, incorporating the implanted bone mineral.

Dr Shah and his colleagues concluded, “Hyperelastic bone has significant potential to be translated to craniofacial reconstructive surgery, where the need for cost-effective bone replacement grafts is enormous.”

With further advancement, it is believed by scientists that this 3D-printed material might offer a useful alternative to autologous bone and commercially available bone substitutes.

“Our study underscores the promising translational potential of this novel strategy for tissue engineering applications, particularly bone regeneration,” the researchers explained further. The researchers highlighted that more experimental studies are required to confirm the hyperelastic bone application for particular types of craniofacial reconstruction.